Antimicrobials Flashcards
Beta-lactam antibiotics mechanism
Interferes with synthesis of bacterial cell wall peptidoglycan
(inhibits transpeptidation enzyme which links peptidoglycan chains)
Beta-lactam eg
Penicillin
Cephalosporins
Carbapenems
Penicillin eg
Co-amoxiclav
Amoxicillin
Penicillin use
Wide -> need to narrow down
Bacterial meningitidis Bone and joint infections soft tissue infections UTI/STI Pneumonia
Cephalosporins eg
Ceftriaxone
Cefuroxime
Cefotaxime
Cephalosporins use
Septicaemia
Meningitis
Carbapenems structure
Carbon atom instead of sulfur (like penicillin has)
Carbapenems use
Penicillin allergy
broad
Carbapenems eg
Meropenem
Imipenem
Ertapenem
Glycopeptide antibiotics mechanism
Inhibit cell wall synthesis (prevents incorporation of brick subunit)
NAG-NAM-PEP
Glycopeptide eg
Vancomycin
Teicoplanin
Glycopeptide use
Gram positive
Orally for treatment of C difficile
(not absorbed in GI)
Antibacterials affecting bacterial protein synthesis
Tetracyclines Aminoglycosides Macrolides Oxazolidinones Lincosamides
Tetracyclines mechanism
Bind to bacterial ribosome
prevent binding of tRNA
Tetracyclines eg
Doxycylcine
Tetracyline
Tetracycline use
Respiratory tract infections
Acne
Chlamydia
Lyme disease
Tetracyclines important
CANNOT give to children under 12, pregnant or breastfeeding women
Stains teeth
Aminoglycosides mechanism
Bind to ribosomes
Misread mRNA
Incorrect amino acids = loss of function
BACTERICIDAL
Aminoglycosides example
Gentamicin
Aminoglycosides use
Gram negative (septicaemia) mostly
Caution aminoglycosides
nephro/ototoxic (kidney/ear toxic)
Strict therapeutic dose
Macrolides mechanism
effect ribosome translocation
bactericidal
macolides examples
Clarithromycin
Erthromycin
Azithtromycin
Macrolides use
similar to penicillin
respiratory pathogens
Oxazolidinones example
Linezolid
Oxazolidinones use
Broad if other antibiotics fail
Gram positive
Anaerobe
Pneumonia, septicaemia
Lincosamides action
effect ribosomal translocation (same as macrolides)
Lincosamides eg
Clindamycin
Lincosamides use
gram positive cocci
penicillin resistant staphylococci
anaerobic bacteria
Quinolones mechanism
Inhibit topoisomerase 2 (bacterial DNA gyrase)
Normal topoisomerase action
usually produces supercoil DNA and permits transcription and replication
Quinolones example
Ciprofloxacin
Levofloxacin
quinolones use
Gran negative, positive and atypical
UTI (complicated)
Gonnorrhoea
side effects quinolones
TAC
Tendinitis (rupture?) Aortic dissection (split walls) CNS effects (convulsions)
Antibacterials that interfere with folate synthesis/action
Sulfonamides
Trimethoprim
Sulfonamides mechamism
structural analogue of PABA
PABA required synthesis of folate and therefore for DNA/RNA synthesis
competes with PABA
enzyme sufronamides compete with PABA for
Dihydropteroate synthetase = less folic acid production
sulfonamides eg
Sulfamethoxazole
Sulfasalazine
Trimethoprim
Folate antagonist
Reversible inhibitor for dihydrofolate reductase
why doesnt trimethoprim not destroy host DNA synthesis?
Binds to bacterial enzyme with higher affinity than human
Trimethoprim use
UTI (careful for reproductive age - neural tube defects)
Metronidazole use
Antiprotozoal
Anaerobic bacteria
Metronidazole effects
Disulfiram like
Avoid using with alcohol
Metronidazole mechanism
not sure - metabolise drug and activates it
blocks nucleic acid synthesis
Antifungals 2 groups
Azoles
Polyenes
Azoles mechanism
Inhibit fungal cytochrome P450 3A enzyme
cant form ergosterol
inhibits replication
Azoles eg
Clotrimazole
Ketoconazole
Fluconazole
Azole use
Candida infections
Polyenes mechanism
doughnut
hole in cell membrane
leaky
polyenes eg
Amphotericin (systemic fungal)
Nyastin (candida)
Anti virals 2
Aciclovir (DNA polymerase inhibitors)
Oseltamivir (neuraminidase inhibitor)
Aciclovir mechanism
phosphorylated by virus
inhibits DNA polymerase
Aciclovir use
Herpes Varicella zoster (chicken pox, shingles)
Oseltamivir mechanism
Inhibits enzyme (neuraminidase) that allows virions to bud and escape host cell
enzyme usually cuts the buds off